Patent application title: Three-Point Clamp for Firearm Mounting Rail

Abstract:

An improved clamping device for a weapon accessory rail of a type having
an elongate mounting structure of generally T-shaped cross-section. The
rail mounting structure may be of a type including a mounting surface and
first and second inclined proximal surfaces on opposite sides of the
mounting surface and first and second inclined distal surfaces adjacent
the first and second proximal surfaces, respectively. The clamping device
includes a mounting shoe with a first inward surface for engaging the
mounting surface and a second inward surface for engaging the second
distal surface. The mounting shoe has an outward facing surface opposite
the first inward facing surface for attaching an accessory device. A cam
lever pivotally movable between first and second positions has a rotary
cam surface engaging a bearing member. The bearing member is movable
between a clamped position and unclamped position in response to movement
of the cam lever to the first and second positions, respectively. In
operation, the bearing member exerts a clamping force on the first distal
surface of the mounting structure in a direction orthogonal to the first
distal surface.

Claims:

1. An improved clamping device for a weapon accessory rail of a type
having an elongate mounting structure of generally T-shaped
cross-sectional shape, the mounting structure including a mounting
surface, first and second proximal surfaces on opposite sides of the
mounting surface and inclined with respect to the mounting surface, a
first distal surface adjacent to and inclined with respect to the first
proximal surface, and a second distal surface adjacent to and inclined
with respect to the second proximal surface, said clamping device
comprising:a mounting shoe including a first inward facing surface for
engaging the mounting surface of the mounting structure and an outward
facing surface opposite the first inward facing surface for attaching an
accessory device thereto;said mounting shoe further including a second
inward facing surface for engaging the second distal surface of the
mounting structure;a cam lever pivotally movable between a first position
and a second position, said cam lever having a rotary cam surface
engaging a bearing member; andsaid bearing member movable to a clamped
position in response to movement of said cam lever to said first position
and an unclamped position in response to movement of the cam lever to the
second position, said bearing member for exerting a clamping force on the
first distal surface of the mounting structure when said bearing member
is in the clamped position, wherein the clamping force exerted by bearing
member is in a direction orthogonal to the first distal surface.

2. The clamping device of claim 1, further comprising:said bearing member
including a bearing plate having a first surface engaging said rotary cam
surface and a second surface opposite said first surface for engaging the
first distal surface.

3. The clamping device of claim 1, further comprising:said bearing member
including a pivot arm pivotally attached to said mounting shoe and
pivotally movable in response to pivoting movement of said cam lever.

5. The clamping device of claim 1, further comprising:one or more springs
urging the bearing member to the unclamped position when the cam lever is
moved to the second position.

6. The clamping device of claim 5, wherein said one or more springs are
selected from one or more coil springs and one or more leaf springs.

7. The clamping device of claim 1, further comprising:said cam lever
pivotally mounted on a pivot cylinder having an axis extending in a
direction parallel to the first distal surface.

8. The clamping device of claim 7, further comprising:a shaft extending
through an opening in said pivot cylinder and having a first end attached
to said mounting shoe.

9. The clamping device of claim 8, further comprising:said shaft extending
in a direction orthogonal to the first distal surface when the clamping
device is attached to the mounting structure.

10. The clamping device of claim 8, further comprising:said shaft
extending in a direction orthogonal to the first distal surface when the
clamping device is attached to the mounting structure and said cam lever
is in the first position.

11. The clamping device of claim 8, further comprising:said first end of
said shaft having external helical threads which engage complimentary
internal threads on said mounting shoe for selectively advancing the
shaft along its axis when the shaft is rotated in a first direction and
retracting the shaft along its axis when the shaft is rotated in a second
direction opposite the first direction.

12. The clamping device of claim 11, further comprising:said complimentary
internal helical threads being formed in a nut received within an opening
formed in said mounting shoe.

13. The clamping device of claim 1, further comprising:said mounting
structure having a plurality of axially spaced apart transverse channels
formed therein; anda protrusion formed on said first inward facing
surface for engaging a selected one of said transverse channels.

14. The clamping device of claim 1, further comprising:means for locking
said cam lever in the first position.

15. The clamping device of claim 1, further comprising:said cam lever
pivotally mounted on a pivot cylinder and including a proximal shaft
portion and a distal shaft portion slidably received within said proximal
shaft portion;said distal shaft portion telescopically movable between a
lever locking position and a lever locking position; andsaid distal shaft
portion having a protrusion engaging a complimentary recess formed in
said pivot cylinder to prevent pivoting movement of said cam lever with
respect to said pivot cylinder when the cam lever is moved to the first
position and the distal shaft portion is moved into the lever locking
position.

16. The clamping device of claim 1, wherein said outward facing surface is
adapted for removably attaching the accessory device.

[0002]The present disclosure relates to clamp device for attachment to a
so-called Picatinny or floating rail structure (e.g., as per standard
MIL-STD-1913) of a type commonly attached to a military firearms for
attaching optical scopes, thermal or laser sights, tactical flashlights,
vertically extending handgrips, or other weapon-mounted accessories.
Referring now to FIG. 1, there appears a conventional elongate Picatinny
rail mount structure 10 having a plurality of mounting members 12, each
having a generally T-shaped cross-section, angularly spaced about the
long axis of the structure 10 and extending radially outward. Each of the
mounting members 12 includes a flat mounting surface 14. The opposite
transverse edges of the mounting members 12 are beveled to form proximal
inclined surfaces 16a and 16b, which are generally outwardly facing, and
distal inclined surfaces 18a and 18b, which are angled with respect to
the respective surfaces 16a, 16b. A plurality of transversely-extending
channels or grooves 20 are formed in each mounting member 12 and spaced
along its length.

[0003]Conventional Picatinny rail clamp devices as illustrated by the
exemplary device shown in FIGS. 2 and 3 commonly employ opposing clamping
members 22 and 24 having inclined surfaces 26 and 28 aligned with and
facing the distal inclined surfaces 18a and 18b of the mounting rail
structure 10 and which are drawn together to bear against the inclined
surfaces 18a, 18b via a transverse clamping force, such as a nut 30
rotatably engaging a transversely extending threaded member 32. Such
prior art devices relying on a transverse clamping force do not maintain
the original orientation when removed and reattached to the mounting
rail. Consequently, aiming or targeting devices that are attached with
conventional clamps may need to re-boresighted with the barrel of the
weapon if removed and reattached to the weapon.

[0004]Thus, it would be desirable to provide a clamp device for securing
an accessory to a firearm via a Picatinny rail interface which would
maintain its original orientation when removed and reattached, thereby
allowing an optical, sighting or other aiming or targeting device to
maintain its boresight when removed and subsequently reattached to the
Picatinny Rail. The present device contemplates improved clamp devices
which overcome the above-referenced limitations and others.

SUMMARY

[0005]An improved clamping device is provided for a weapon accessory rail
of a type having an elongate mounting structure of generally T-shaped
cross-section shape. The rail mounting structure may be of a type
including a mounting surface and first and second proximal surfaces on
opposite sides of the mounting surface and inclined with respect to the
mounting surface. A first distal surface of the rail mounting structure
is adjacent to and inclined with respect to the first proximal surface
and a second distal surface is adjacent to and inclined with respect to
the second proximal surface. The clamping device includes a mounting shoe
defining a channel and including a first inward facing surface for
engaging the mounting surface of the mounting structure. The mounting
shoe has an outward facing surface opposite the first inward facing
surface for removably attaching an accessory device and further includes
a second inward facing surface for engaging the second distal surface of
the mounting structure. A cam lever is pivotally movable between a first
position and a second position and has a rotary cam surface engaging a
bearing member. The bearing member is movable to a clamped position in
response to movement of the cam lever to the first position and an
unclamped position in response to movement of the cam lever to the second
position. In operation, the bearing member exerts a clamping force on the
first distal surface of the mounting structure which is in a direction
orthogonal to the first distal surface.

[0006]One advantage of the clamping devices in accordance with the present
disclosure is found in that the clamping force is exerted in a direction
orthogonal to the distal inclined clamping surface of the rail interface
thereby providing secure retention of an accessory device.

[0007]Another advantage of the presently disclosed clamping device resides
in the ability to maintain a precise alignment upon removal and
reattachment of the device. In this manner, precisely aligned or
boresighted accessory devices such as scopes, sights, or other sighting,
aiming or targeting devices may be temporarily removed and reattached
without the need for realigning the device.

[0008]Still further advantages and benefits of the present invention will
become apparent to those of ordinary skill in the art upon reading and
understanding the following detailed description of the preferred
embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]The invention may take form in various components and arrangements
of components, and in various steps and arrangements of steps. The
drawings are only for purposes of illustrating preferred embodiments and
are not to be construed as limiting the invention.

[0012]FIGS. 4 and 5 are generally front and rear pictorial views,
respectively, of a first exemplary embodiment clamping apparatus herein
shown in secured position on a Picatinny rail mounting structure.

[0013]FIGS. 6 and 7 are isometric views of the clamp device embodiment
appearing in FIGS. 4 and 5, in locked and unlocked position,
respectively.

[0014]FIGS. 8 and 9 are elevational views of the clamp embodiment
appearing in FIGS. 4-7, in locked and unlocked position, respectively.

[0015]FIG. 10 is an elevational view of the clamp embodiment appearing in
FIGS. 4-9 in clamped position on a Picatinny rail interface.

[0016]FIG. 11 is an enlarged isometric view of the clamp embodiment
appearing in FIGS. 4-10 embodiment in locked position, taken generally
from the bottom.

[0017]FIG. 12 is an exploded isometric view of the clamp embodiment
appearing in FIGS. 4-11.

[0018]FIG. 13 is an enlarged view of the embodiment appearing in FIGS.
4-12, wherein the locking cam lever is shown in partial cross-section.

[0019]FIG. 14 is an isometric view of a second exemplary embodiment
clamping device, shown in the unlocked position.

[0020]FIG. 15 is an exploded isometric view of the second embodiment
clamping device shown in FIG. 14.

[0021]FIGS. 16 and 17 are isometric views of a third exemplary embodiment
clamping device, shown in the locked and unlocked position, respectively.

[0022]FIGS. 18 and 19 are elevational views of the clamp embodiment
appearing in FIGS. 16 and 17 on a rail mounting structure, shown in the
locked and unlocked position, respectively.

[0023]FIGS. 20 and 21 are isometric views of the clamp embodiment
appearing in FIGS. 16-19, taken generally from the bottom and shown in
the locked and unlocked position, respectively.

[0024]FIG. 22 is an exploded isometric view of the clamp embodiment
appearing in FIGS. 16-21.

[0025]FIGS. 23 and 24 are isometric views of a fourth exemplary embodiment
clamping device, in locked and unlocked position, respectively.

[0026]FIG. 25 is an elevational view of the clamp embodiment appearing in
FIGS. 23 and 24, shown on a rail mounting structure, in the locked
position.

[0027]FIG. 26 is an elevational view of the clamp embodiment appearing in
FIGS. 23-25 in the unlocked position.

[0028]FIG. 27 is an isometric view of the clamp embodiment appearing in
FIGS. 23-26 in locked position, taken generally from the bottom.

[0029]FIG. 28 is an exploded isometric view of the clamp embodiment
appearing in FIGS. 23-27.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030]Referring now to FIGS. 4-13, a first exemplary embodiment
three-point clamp in accordance with the present disclosure includes a
mounting shoe 42 and a movable clamping member 44. The mounting shoe 42
includes an upper (in the orientation shown in FIG. 4) surface 46 having
apertures 48, which are preferably tapped or internally threaded openings
for securing an accessory or device (not shown) to the surface 46 for
removable mounting on the weapon rail interface using the clamping member
40.

[0031]The mounting shoe 42 defines an axial channel 50 defined by a first
inner surface 52 opposite the upper surface 46 for engaging the mounting
surface 14 in aligned and facing contacting relation when the unit 40 is
attached to a weapon rail 10 mounting member 12. The axial channel 50 is
also defined by a second inner surface 54 for engaging distal inclined
surface 18b in aligned and facing contacting relation when the unit 40 is
attached to a weapon rail 10 mounting member 12.

[0032]In the depicted embodiment 40, a protruding member 56 may be secured
to the inner surface 52 via a threaded fastener 58. The protruding member
56 is adapted to be received within a selected one of the grooves 20 to
prevent axial movement of the clamping member 40, e.g., due to recoil of
the firearm when a round is fired.

[0033]In the depicted embodiment, the movable member 44 comprises a
bearing plate, which is movable between a first, unclamped position and a
second, clamped position. The bearing plate 44 includes a first, rail
engaging surface 60, which engages the distal inclined surface 18a in
aligned and facing contacting relation when the unit 40 is attached to a
weapon rail 10 mounting member 12. The bearing plate 44 also includes cam
engaging surfaces 61, which are opposite the rail engaging surface 60.

[0034]The bearing plate 44 includes an opening 62 receiving a drawbar 64
such that the bearing plate 44 is slidable therealong. The bearing plate
44 is captured between a rotatable cam member 66 and the mounting shoe
42. The cam member 66 is rotatable between a locked position and an
unlocked position, via a lever 102, a preferred embodiment of which is
described in greater detail below. The bearing plate 44 is thus
selectively moved between the clamped position and unclamped position
when the cam 66 is moved between the locked and unlocked position,
respectively.

[0035]The cam member 66 includes an offset opening 68 receiving a pivot
pin or cylinder 70 about which the cam member 66 pivots or rotates. The
drawbar 64 passes through an opening 72 in the pivot pin 70 and is
retained by an enlarged head portion 74 of the drawbar 64. A spring
member 76 includes spring arms 78 and is secured to the bearing plate 44
via threaded fasteners 80 engaging aligned openings 82 and 84 in the
spring member 76 and bearing plate 84, respectively.

[0036]The drawbar 64 additionally passes through an opening 86 in the
spring member 76 and includes a threaded end 88 which rotatably engages
an internally threaded nut 90 received within an opening 91 in the
mounting shoe 42. The nut 90 may include a flange portion 93 to retain
the nut in the opening 91. Rotation of the drawbar 64, e.g., via a slot
92 for receiving a tool formed in the head 74, allows for adjustment of
the unit by selectively advancing or retracting the drawbar 64 to fine
tune the effective length of the draw bar 64 and thereby precisely
position the plate 44 when in the lever 102 is moved into the clamped
position. In this manner, the device 40 may be adjusted to accommodate
minor variations from one rail interface structure 10 to another.

[0037]A threaded set screw 94 may be rotatably received within a threaded
opening 96 in the pivot cylinder 70. The set screw 94 may be rotated
until it bears against the drawbar 64 so as to retain the drawbar 64 at a
desired rotational position and prevent further rotation of the drawbar
64 relative to the nut 90, e.g., due to vibrational forces when the
weapon is fired.

[0038]The spring arms 78 urge the bearing plate 44 against peripheral cam
surfaces 98 on the cam member 66, whereby the bearing plate is
selectively moved toward or away from the distal inclined surface 18a in
response to unlocking rotation of the cam member 66. The bearing surface
60 lies in a plane which is orthogonal to the axis 100 of the drawbar 64
and thus, the surface 60 is parallel to the facing distal inclined
surface 18a. Thus, the bearing plate 44 travels in a direction which is
orthogonal to the adjacent inclined surface 18a and exerts a force which
is normal to or orthogonal to the plane of the distal inclined surface
18a when the cam 66 is rotated to the locked or clamped position. In this
manner, the device 40 provides a secure clamping force which is
orthogonal to each of the two opposing distal inclined rail surfaces 18a,
18b and the upper mounting surface 14 of the mounting structure 12.

[0039]A cam lever 102 is provided for rotating the cam member 66. In the
depicted preferred embodiment, the cam lever 102 is a locking cam lever
and includes a hollow, proximal shaft portion 104 and a hollow distal
shaft portion 106. The distal shaft portion 106 is slidably received
within the hollow proximal shaft portion 104 and includes an end 108
which engages a notch 110 formed on the pivot cylinder 70 when the lever
is moved to the clamped position and the distal shaft portion 106 is
completely received within the proximal shaft portion 104. When the end
108 of the distal shaft portion 106 engages the notch 110, the shaft 102
is locked, e.g., preventing inadvertent movement of the lever 102 and
thereby preventing inadvertent unclamping of the unit 40.

[0041]In operation, the pin 112 engages the outer leg 118 of the U-shaped
openings 116 when the lever 102 is in the locked position. To unlock the
lever 102, the distal shaft portion 106 is rotated until the pin 112 is
received within the axial-extending portion 120 of the U-shaped channels
116. A spring 124, which is captured within the hollow interior portion
of the distal shaft portion 106 by the retaining pin 112 bears against
the pin 112 and urges or biases the distal shaft portion 106 toward the
unlocked position. When the lever 102 is unlocked, the end 108 disengages
the notch 110 and the cam member 66 may be rotated to the unlocked
position. To lock the lever 102, the lever 102 is rotated to the locked
position and the distal shaft portion 106 is moved inwardly to compress
the spring 124 until the end 108 engages the notch 110. The distal shaft
portion 106 is then rotated until the pin 112 is received within the
outer leg portion 118 of the U-shaped channels 116.

[0042]Referring now to FIGS. 14 and 15, there is shown a clamping device
140 according to a second exemplary embodiment, which is similar to the
clamping device embodiment 40 appearing in FIGS. 4-13, except that coil
springs are used in place of the spring fingers 78 (see FIG. 12) for
biasing the bearing plate to the unclamped position when the cam lever is
moved to the unlocked position. Components or features common to the
first and second embodiments 40 and 140 are designated with like
reference numerals in the drawing figures. Such like reference numerals
appearing in FIGS. 14 and 15 are as described by way of reference to
FIGS. 4-13 unless indicated otherwise.

[0043]The clamping device 140 includes a mounting shoe 142 and a movable
clamping member 144. The mounting shoe 142 includes an upper (in the
orientation shown in FIGS. 14 and 15) surface 146 and apertures 148,
e.g., tapped or threaded openings for securing an accessory device (not
shown) thereto.

[0044]The mounting shoe 142 defines an axial channel 150 defined by a
first inner surface 152 opposite the upper surface 146 for engaging the
mounting surface 14 of a rail structure 12. The axial channel 150 is also
defined by a second inner surface 154 for engaging the adjacent distal
inclined surface 18b. The movable clamping member 144 is movable into
clamped position to engage the opposite distal inclined surface 18a.

[0045]A protruding member 56 may be secured to the inner surface 152 via a
threaded fastener 58 for engaging an aligned one of the grooves 20 to
prevent axial movement of the clamping member 140, e.g., due to firearm
recoil.

[0046]The bearing plate 144 is movable between a first, unclamped position
and a second, clamped position and includes a first, rail engaging
surface 160, which engages the distal inclined surface 18a which is on
the opposite side of the structure 12 as the rail surface 18b, which is
engaged by the surface 154. The bearing plate 144 also includes cam
engaging surfaces 161 opposite the rail engaging surface 160.

[0047]The bearing plate 144 includes an opening 162 receiving a drawbar 64
such that the bearing plate 144 is slidable therealong. The bearing plate
144 is captured between a rotatable cam member 66 and the mounting shoe
142. The cam member 66 is rotatable between a locked position and an
unlocked position. The bearing plate 144 is thus selectively moved
between the clamped position and unclamped position when the cam 66 is
moved between the locked and unlocked position, respectively.

[0048]The cam member 66 includes an offset opening 68 receiving a pivot
pin or cylinder 70 about which the rotation of the cam member pivots or
rotates. The drawbar 64 passes through an opening 72 in the pivot pin 70
and is retained by an enlarged head portion 74. Spring rods or pins 180
are secured to the bearing plate 144 on opposite sides of the drawbar 64,
e.g., via a press fit, snap fit, friction fit, or other rigid attachment,
within corresponding openings 184 in the bearing plate 144. The distal
ends of the pins 180 are slidingly received within openings 181 in the
mounting shoe 142. Springs 178 are coaxially received about the pins 180
and are captured between the bearing plate 144 and the mounting shoe 142
to urge the bearing plate 144 toward the unclamped position.

[0049]The drawbar 64 includes a threaded end 88 which rotatably engages a
threaded nut 90 received within an opening 191 in the mounting shoe 142.
Rotation of the drawbar 64, e.g., via a tool-engaging slot 92 provides
for fine adjustment of the device as described above.

[0050]The springs 178 urge the bearing plate 144 against peripheral cam
surfaces 98 on the cam member 66, whereby the bearing plate may be
selectively moved toward and away from the distal inclined surface 18a by
rotating the cam member 66. The bearing surface 160 lies in a plane which
is orthogonal to the axis 100 of the drawbar 64 and thus is parallel to
the facing distal inclined surface 18a. Thus, the bearing plate 144
exerts a force which is normal to or orthogonal to the facing distal
inclined surface 18a when the cam 66 is rotated to the locked or clamped
position.

[0051]A cam lever 102 is provided for the rotation of the cam member 66
and may be a locking cam lever 102 is as described above by way of
reference to the locking cam lever 102 shown and described above by way
of reference to FIGS. 4-13.

[0052]Referring now to FIGS. 16-22, a third exemplary embodiment clamping
device 240 is shown, which is similar to the embodiment 140 appearing in
FIGS. 14 and 15, but without the locking lever assembly. Components or
features described above by way of reference to the first and second
embodiments 40 and 140 and common to the third embodiment 240 are
designated with like reference numerals in the drawing figures. Such like
reference numerals appearing in FIGS. 16-22 are as described above by way
of reference to the first and/or second embodiments unless indicated
otherwise.

[0054]The mounting shoe 242 defines an axial channel 250 defined by a
first inner surface 252 opposite the upper surface 246 for engaging the
mounting surface 14 of a rail structure 12. The axial channel 250 is also
defined by a second inner surface 254 for engaging the adjacent distal
inclined surface 18b. The movable clamping member 144 is movable into
clamped position to engage the distal inclined surface 18a.

[0055]A protruding member 56 may be secured to the inner surface 252 via a
threaded fastener 58 for engaging an aligned one of the grooves 20 to
prevent axial movement of the clamping member 240, e.g., due to firearm
recoil.

[0056]The cam lever 202 includes a lever portion 206 and a cam portion
266. The cam portion 266 is pivotally mounted to a pivot cylinder or pin
270 received within an offset opening 268. The cam portion 266 includes
cam surfaces 298, which bear against bearing surfaces 161 of the bearing
plate 244.

[0057]A draw bar 64 including a shaft portion with threaded end 88 and an
enlarged head portion 74 is received through an opening or channel 272 in
the cylinder 270, an opening 162 in the bearing plate 144 and an opening
291 in the mounting shoe 242. An internally threaded nut 90 within the
opening 191 rotatably receives the threaded end 88 of the draw bar 64.
The nut 90 includes an enlarged or flange portion 93 to retain the nut 90
within the channel 291.

[0058]The drawbar 64 may be rotated relative to the nut 90, e.g., via tool
engaging a slot 92, to adjust the unit as described above. A set screw 94
(see, FIG. 15) may be provided to prevent further inadvertent rotation of
the drawbar 64 once it has been adjusted, as described above.

[0059]Rods or pins 180 are secured to the bearing plate 144, e.g.,
preferably via a press fit, snap fit, or friction fit within
corresponding openings 184 on the bearing plate 144, or, may be otherwise
rigidly attached to the bearing plate 144. The distal ends of the pins
180 are slidingly received within openings 281 in the mounting shoe 242.
Each of the pins 180 carries a coil spring 178.

[0060]In operation, when the lever 202 is pivoted from the unlocked
position to the locked position, the cam surfaces 298 bear against the
surfaces 161 of the bearing plate 144 causing the bearing plate 144 to
slide inwardly toward the mounting shoe 242, against the urging of the
springs 178.

[0061]A lever guard 253 is secured to the mounting shoe 242 via one or
more threaded fasteners 255 engaging openings 251 in the lever guard and
openings 249 in the mounting shoe 242. The lever guard 253 covers the
lever 202 to prevent snagging or inadvertent release of the lever 202.
The lever guard 253 may also include a tab or protrusion 257, which is
adapted to engage a complimentary and aligned recess 259 formed on the
lever 202. The tab 257 and recess 259 may be configured to permit the
lever 202 to be readily moved into the locked position while resisting
movement of the lever 202 from the locked position to the unlocked
position, e.g., via ramping or inclination of the sliding surfaces. For
example, the tab 257 and the recess or depression 259 may be shaped such
that a slight upward lifting of the lever guard 253 will release the tab
257 from the recess 259 and permit movement of the lever 202 from the
locked position to the unlocked position.

[0062]During operation, the inclined surface 254 is in aligned and facing
relation to the inclined surface 18b on one side of the rail mount member
12. The bearing plate 144 includes a bearing surface opposite the cam
engaging surfaces 161, which, during operation, is in aligned and facing
relation to the inclined surface 18a on the other side of the rail mount
member 12. The direction of the bearing plate 144 movement and the
direction of the force exerted by the cam 266 are a direction that is
orthogonal to the adjacent inclined surface 18a.

[0063]Referring now to FIGS. 23-28, a fourth exemplary embodiment clamping
device 340 is shown. Components or features described above by way of
reference to the first, second, and/or third embodiments 40, 140, and 240
which are common to the fourth embodiment 340 are designated with like
reference numerals in the drawing figures. Such like reference numerals
appearing in FIGS. 23-28 are as described by way of reference to the
above-described embodiments unless indicated otherwise.

[0064]The fourth embodiment clamping device 340 includes a mounting shoe
member 342, a pivoting member 343, and a cam lever 302. The mounting shoe
342 includes hinge members 345 and the pivot member 343 includes hinge
members 347. Pivot pins 363 extend through openings 365 and 367 in
adjacent ones of the hinge members 347 and 345, respectively.

[0065]Apertures 348, which are preferably tapped or internally threaded
apertures, are provided to secure an accessory (not shown) to be mounted
on the weapon. Springs 378 are captured between the mounting shoe 342 and
the pivoting member 343 to bias the pivot member 343 outward and to cause
the pivot member 343 to pivot about the pivot pins 363 to the outward,
open position when the lever 302 is moved to the unlocked position.

[0066]The lever 302 is pivotally mounted to a pivot cylinder or pin 270
and includes a cam portion 366 and a lever portion 306. The cam portion
includes an offset opening 368 for pivotal receipt of the pivot cylinder
270 and cam surfaces 398 which bear against cam engaging surfaces 361 of
a bearing plate 344, which is carried on the pivot member 343.

[0067]A draw bar 64 including an elongate shaft portion having a threaded
end 88 and an enlarged head portion 72 is received through an opening 272
in the cylinder 270, an opening 362 in the bearing plate 344, an opening
or channel 369 in the pivot member 343, and between the hinge members
345.

[0068]An internally threaded nut 390 rotatably receives the threaded end
88 of the draw bar 64. The nut 390 includes integral pins 393 and is
pivotally received in a cavity 391 formed in the mounting shoe 342. The
drawbar 64 may be rotated, e.g., using a tool engaging a slot 92 to fine
tune the device 340 by selectively advancing or retracting the drawbar
64, e.g., to accommodate minor variations from one rail interface
structure 10 to another as described above.

[0069]In operation, when the lever 302 is pivoted from the unlocked
position to the locked position, the cam surfaces 398 bear against the
cam engaging surfaces 361 of the bearing plate 344, which in turn causes
the pivoting movement of the pivoting member 343. Movement of the lever
306 to the locked position causes the pivot member 343 to pivot inwardly
about the pivot pins 363 against the urging of the springs 378. The lever
portion 306 of the cam lever 302 may include a notch 359 formed therein
receiving the pivot member 343 when the lever is in the locked or clamped
position to prevent snagging or inadvertent release.

[0070]The mounting shoe 342 includes an axially extending channel 350
defined by an inclined surface 354 and an adjacent surface 352, which is
opposite an upper mounting surface 346. In operation, the inclined
surface 354 is in aligned and facing relation to the inclined surface 18b
on one side of the rail mount member 14 and the surface 352 is aligned
and facing the upper mounting surface 14 of the rail structure 12. One or
more protrusions 356 sized to engage one or more of the grooves or
channels 20 may be provided on the surface 352 to prevent axial movement
of the clamping apparatus, e.g., due to recoil when the weapon is fired.

[0071]The pivot member 343 includes an inclined bearing surface 360 which
is in aligned, facing, and contacting relation to the inclined surface
18a on the opposite side of the rail mount member 12 when the clamp is
secured to the rail structure 12. Because the pivot member 343, cam lever
202, and drawbar 64 all pivot during clamping, the force exerted by the
bearing surface 360 on the rail mount surface 18a is orthogonal to the
plane of the surface 18a.

[0072]In the illustrated embodiments, the fixed inclined surface of the
mounting shoe is shown engaging the distal inclined surface 18b of the
rail structure 12 and the moveable clamping member is shown engaging the
distal inclined surface 18a. However, it will be recognized that the
clamping member may be reversed if desired, e.g., to accommodate left and
right handed marksmen or otherwise depending on which side of the rail
the user desires to position the locking and unlocking lever.

[0073]The invention has been described with reference to the preferred
embodiments. Modifications and alterations will occur to others upon a
reading and understanding of the preceding disclosure herein, whereby it
is to be distinctly understood that the foregoing descriptive matter is
to be interpreted merely as illustrative of the invention and not as a
limitation.